≥0.5 g/dL for IgG, IgA myeloma and ≥0.05 g/dL for IgD myeloma or urine M-protein level ≥ 0.2 g excreted in a 24-hour collection sample or In case of progressive disease without complete remission during preceding treatment: > 25% increase of serum monoclonal paraprotein or urine M-protein in comparison to the preceding monoclonal paraprotein (M-protein)nadir in serum /urine M-protein nadir in a 24 hour collection sample